Monday, 7 November 2005
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Identification and Mapping of Quantitative Trait Loci Associated with Crop Response to Water-Deficit Stress in Soybean [Glycine Max (L.) Merr.].

Sandeep Bhatnagar1, C. Andy King1, Larry Purcell1, and Jeffery D. Ray2. (1) University of Arkansas, Crop Soil and Env., Fayetteville, AR 72703, (2) USDA-ARS, 141 Experiment Station Road, Stoneville, MS 38756

Soybean genotypes have been reported to differ in the onset and severity of canopy wilting in response to water-deficit stress. Identification of genomic regions associated with slow wilting trait could be beneficial in selecting for increased drought tolerance in soybean. The objectives of this study were to determine the heritability of differential canopy wilting and to identify and map associated quantitative trait loci. Eighty one F5 derived recombinant inbred lines (RILs) from a cross between Jackson x KS4895 were visually rated for canopy wilting (0 = no wilting, 3 = severely wilted and 5 = plant death) in non-irrigated environments at Sttutgart, AR in 2000, 2003 and Sandhills, NC in 2002. DNA of RILs was screened with 135 polymorphic SSR markers. Entry mean heritability was 0.72 among all three environments. Initial single point analysis identified 16 markers significantly associated (P<0.05) with slow wilting at all environments. Interval mapping identified one major QTL (P < 0.001) linked to SSR marker Sat044 in linkage group K (LOD > 3.0, R2 = 17.0).

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